• Journal of Pharmaceutical Investigation
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• 제26권2호
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• pp.137-144
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• 1996

The study was carried out for the preparation and evaluation of a buoyant hydrogel matrix (BHM), which is buoyant in a neutral or in pH 2.0 buffer solution, by the aspects of buoyancy, swelling, and drug release. Physical mixtures of HPC and CP in various molar ratio were employed as a mucoadhesive polymer which swells and controls the rate of drug release. Anhydrous citric acid and sodium bicarbonate in the molar ratio of 1:3 were employed as effervescing agents which provide a buoyancy for the mucoadhesive polymeric matrix. The buoyancy in vitro was expressed as both floating time$(T_{fl})$ and surfing time$(T_{sf})$, which are the time required for floating from the bottom to the surface of the medium and the time to keep the floated state at the surface of medium during release studies, respectively. A close relationship was observed between the buoyancy and the amount of effervescing agent added. $T_{fl}$ of the buoyant hydrogel matrices were decreased to about 10 seconds linearly with increasing the amount of effervescing agent in the range of 5 to 15%. $T_{sf}$ of the buoyant hydrogel matrices were varied from 1 to 3 hr depending on the amount of effervescing agent. The swelling was observed by changes in diameter of the buoyant hydrogel matrices in distilled water or acidic buffer solution, resulted in dependences on pH and the amount of effervescing agents. The release of hydrochlorothiazide from the buoyant hydrogel matrices were followed by apparent zero-order kinetics, while the buoyant hydrogel matrices were floated at the surface and maintaining their swollen shapes.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.463-467
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• 2004

Rosette-type diffusers with four-ports per riser are constructed in relatively shallow water in Korea. However, the trajectorial bending phenomena due to lower-pressure inside the surrounded buoyant jets on the riser was not considered in most models and was not observed without any experimental results. The buoyant jet behavior affected by the bending effect where there have been growing interests need to be verified experimentally and need to be preceded in the analysis of the characteristics of the buoyant jets oil a riser. The hydraulic model experiments have been carried out to investigate the characteristics of the behavior of horizontal buoyant jets discharged from a Rosette-type riser with four ports as well as single port over a certain range of the experimental conditions including initial momentum and initial buoyancy using LIF (Laser Induced Fluorescence) system to obtain concentration fields. The intensity of the fluorescent light in each pixel on the images obtained from LIF system with the tracer of Rhodamine H was converted to the local dye concentration with a set of calibration procedures to account for the non-uniform distribution of light intensity and the attenuation of light energy by water medium. The experimental results shows that the trajectories from Your ports tend to bend more and more to the inner side with the increase of the densimetric Froude number while the buoyant jet from a single port rises up without any bending phenomena. The previous models, VISJET and Seo et al. (2002), do not simulate the trajectories well except the region before the bending section. This study will focus on the analysis of the behavior of the buoyant jets for mainly a Rosette-type riser by conducting hydraulic model experiments using LIF system.

• Journal of Microbiology and Biotechnology
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• 제11권2호
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• pp.326-328
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• 2001

Pseudomonas diminuta (ATCC 19146) has been typically used in the bacterial challenge test for validation of the sterilizing filtration process. Cell size is critical for determining the retention characteristics of membrane filters with pore-size of $0.2{\mu}m$. The changes of cell sizes after osmotic shocks at 150, 260, 500, and 700 mosM were measured by a particle size analyzer and the changes of their buoyant densities were analyzed with a Percoll gradient. The results indicated that there were no significant differences when cells were cultured in 260 mosM medium and osmotically shocked at 500 and 700 mosM. However, the osmotically shocked cells at 150 mosM showed a 38% increase of the cell size compared to the cells at 260 mosM. From these study, we concluded that the worst case condition for validation of a sterilizing filter would be 500 mosM, not because of changes in the cell size, but due to decrease in cell viability under those conditions.

• 상하수도학회지
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• 제19권2호
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• pp.149-154
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• 2005

Conventionally used flocculation tanks require large space and high energy requirement for mixing. Static flocculators using gravel bed filter operate at a lower flow rate ($5-10m^3/m^2{\cdot}h$). Further, the cleaning of this system is difficult. A novel high rate static flocculator/filter developed at UTS packed with buoyant media such as polystyrene, polypropylene has been found to operate at higher filtration rates (30-45 $5-10m^3/m^2{\cdot}h$). They can easily be cleaned with minimal energy. Detailed experiments conducted with an artificial kaolin clay solution show that buoyant media is an excellent static flocculator in producing uniform filterable microflocs (12-15 m) even when it is operated at a high rate of 30-40 m/h. Detailed filtration experiments were conducted in a wastewater treatment plant to treat the biologically treated effluent with a floating media of depth of 120 cm. This filter was able to remove majority of phosphorus and remaining solids. It reduced significantly the fecal coliforms and fecal streptoccoci, thus requiring less amount of chlorine for disinfection. The advantage of this system is the low energy and water requirement for cleaning of filter bed. The periodic backwash adopted 30 seconds air and water and 30 seconds water cleaning every 90 minutes filter operation. Thisis equivalent to 1-2% of filtered water production. Mechanical cleaning system on the other hand, requires very low energy requirement (<1% of filtered water production).

• 한국기계연구소 소보
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• 통권14호
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• pp.157-168
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• 1985

In cargo vessels, hatch covers are used to prevent sea water from penetrating into the cargo hold and to keep the vessels buoyant. And also they can be used as cargo loading devices as in container ships. In this paper, hatch covers are classified according to their operation method and their characteristics are briefly demonstrated. Systematic description on the scantling of the hatch cover panel and how to determine the capacity of the hydraulic power system fir folding hatch cover panels are also presented. The hydraulic power system is selected from the result of dynamic analysis of the movements of the hatch cover panels when stored on the upper deck. The hatch coaming height is determined as shortly as the hydraulic cylinders can be installed. This study deals with the hatch cover system of the medium sized multi-purpose cargo vessel, but the results of this study can be applied to large-sized cargo vessels with a slight change of the input data in the calculations. Further research on the high pressure pump, hydraulic cleating system and hydraulic piping will realize domestic production of the whole hatch cover system which have been supplied from foreign makers until now

• 대한설비공학회지:설비저널
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• 제16권1호
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• pp.103-108
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• 1987

The heat transfer processes taking place in the side wall of a thermocline enclosure have been analyzed for idealized conditions based on the assumption that, at any instant time, side wall heat transfer processses are independent of the thermocline bulk motion. However, the axial tempera-ture distribution in the thermocline core provides the means for specifying the liquid medium-side boundary condition to the enclosure side wall. A picture is drawn which reflects the side wan response to thermocline bulk motion within the frame work of a quasi-steady analytic approach. For valves of the parameters typical of systems of engineering interest, the analysis shows that a significant amount of heat transfer short - circuiting can take place along the side wall enclosure. This phenomenon is favored by high values of $H_l$ and low values of P and $H_g$ respec-tively. The location of the point of zero normal heat flux on the side wan can be expected to mark, approximately, the region of confluence of two sidewall boundary flows respectively driven by the buoyant effects.

• 수산해양기술연구
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• 제55권2호
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• pp.162-171
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• 2019

This study is aimed to develop an improved shellfish dredge vessel considering the increase of the fishing safety and welfare of fishermen in Jeonnam province. We visited five fishing village societies in Korea, and conducted field surveys and survey questions to investigate the current status. In order to solve the problems presented by the investigation, a general arrangement of the improvement vessel was written and adopted after meeting between the fishermen and research team, and calculated the initial stability in five loading conditions by using the Napa program. As a result of field surveys and survey questions, the existing vessel have buoyant materials under the bow and the warp pass through the wheel-house. In addition, most fishing equipment and nets are concentrated on a narrow stern, making it difficult to work efficiently. According to the survey, fishermen also responded that operation of casting and hauling is very inconvenient. The fishing equipment of the improvement vessel was rearranged, the size of the wheel-house and the crew room was increased, and we secured a basic welfare space. As a result of the initial stability test, the stability criteria of the fishing vessel were satisfied in all loading condition.

• 한국미생물·생명공학회지
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• 제28권3호
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• pp.180-184
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• 2000

제지폐수 처리장에는 공정내에서 순환하는 분산성 미생물이 존재하는데 환경조건에 따라 이상중식 현상이 일어나 처리수질의 악화와 악취가 발생되는 현상이 발견되었다. 본 연구에서는 이러한 문제를 일으키는 분산성 미생물을 파악한후 우검종 분산성 미생물을 분리동정하고 각 폐수처리 공정중에서 호기 및 혐기적 미생물의 생태분석 및 그 생육특성을 조사하여 이를 토대로 안정적인 폐수처리를 위한 미생물관리 모델시스템 개발의 기초적인 연구를 수행하였다. 제지폐수내 1차 처리수중 주요 우점종 분산성균들의 분리동정 결과 호기성균으로 Pseudomonas carboxydohydrogena, Cardiobacterim hominis. Micrococcus lylae, Xantomonas cam-pestris pv juglandis, Micrococcus diversus, Comamaonas terrigena, 혐기성균으로는 Streptococcus bovis, Prevotella buccae등의 균이 동정되었다 3회의 분석때마다 서로 다른 buccae등의 균이 동정되었다. 호기적 균이 혐기성 균보다 더 많은 종류가 검출되었다 이중 주요 균의 생리특성을 관찰한 결과 온도는 $37^{\circ}C$에서 생육이 가장우수하였고 적정 pH는 균종에 따라 다르게 나타났으며 특히 1차 폐수처리시에 첨가되는 alumi-nium sulfate에 의한 sulfate의 요구 균주가 많았다 따라서 제지 폐수내의 분산성 미생물은 매우 다양한 균들로 이루어져 있으며 외부의 환경변화에 의하여 microflora 가 변하고 있음을 확인할 수가 있었다 그리고 이들 호기적처리 공정중에서도 많은 혐기성 미생물이 생육하들 호기적처리 공정중에서도 많은 혐기성 미생물이 생육하고 있으며 이들이 폐수처리에 많은 역할을 하고 있는 것으로 나타났다. 특히 1차 침전조에서의 긴 체류시간에 의하여 상등액에서 원폐수보다 호기성미생물보다 혐기성미생물의 생육이 3배나 많이 이루어졌고 1차침전조에서의 긴 체류시간에 의하여 상등액에서 원폐수보다 호기성미생물보다 혐기성미생물의 생육이 3배나 많이 이루어졌고 1차침전조 하부 슬러지액에서는 혐기성균이 10배나 많이 존재하였다 따라서 혐기성균이 침전된 유기물로부터 황화수소가스와 이산화탄소등의 가스를 발생시키고 이 가스가 하부에서 상부로 부상하면서 미생물의 침전성을 악화하여 분산성미생물을 증가시켜 폐수처리효율을 떨어뜨리며 아울러 심한 악취까지 발생시킬 것으로 사료된다.

• Restorative Dentistry and Endodontics
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• 제29권5호
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• pp.479-484
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• 2004

감염근관내 spirochetes의 존재 유무에 대한 논란이 많았으나 최근 PCR을 사용한 세균검출 실험에서 Treponema denticola 균주가 감염근관의 50%이상의 경우에서 발견됨에 따라 이 세균이 치수 및 치근단 질환의 병인과정에 관여하는 지에 대한 관심이 높아지고 있다. 이와 관련하여 Shenker 등이 T. denticola의 sonicated extract에서 순수분리된 면역억제 단백질 (immunoinhibitory protein)이 T 임파구의 proliferation을 방해함을 보고한 바 있다. 하지만 이 세균성 단백질이 T 임파구의 기능에 어떤 영향을 미치는 지에 대한 연구는 부족한 실정이다. 따라서 T. denticola의 면역억제 단백질이 처리되기 전과 후의 T 세포에서 분비되는 cytokine Interleukine-2와 Interleukine-4의 발현 정도를 비교하여 그 작용기전을 밝히는 것이 본 연구의 목적이다. Treponema denticola LL2513를 혐기성 상태에서 TYGVS 배지에 배양한 다음 PBS 세척과 lyophilize 과정을 거친 후 sonication을 시행한다. 이 과정을 거쳐 추출된 상층액이 T. denticola의 면역억제 단백질인 sonicated extract이다. 실험을 위해 건강한 혈액 공여자로부터 T 세포를 Buoyant density 방법으로 추출해 낸 다음 24-well plate에 100만개의 세포를 주입한 다음 Group 1에는 2% FBS의 medium만으로 배양하고, Group 2에는 100 $\mu$l의 PHA로만 증식 자극을 하였고, Group 3에는 PHA처리 전 sonicated extract로 T세포를 자극하였다. 72시간 동안 배양한 다음 상층액을 추출하여 ELISA assay를 사용하여 IL-2와 IL-4의 발현정도를 측정하였다. PHA로 자극받은 Group 2에서는 IL-2와 IL-4가 대조군인 Group 1에서보다 높은 수준으로 발현되었다. 하지만 $12.5{\;}\mu\textrm{g}/ml$의 T. denticola sonicated 추출물로 전처리한 Group 3에서는 IL-2와 IL-4의 수준이 유의성있게 억제되어 발현되었다 (p < 0.05). 이러한 결과를 통하여 T. denticola에서 추출된 면역억제 단백질이 Th1과 Th2의 cytokine 분비 기능을 억제하는 것으로 확인 되었으며 이 기전이 감염 근관에서 발견되는 T. denticola의 치수 및 치근단 질환에 대한 병인기전과 관련이 있는 것으로 사료된다.